Flotation device



Nov. 24, 1964 CONDITIONING CELL FLOTATION CELL COAL BEARING FROTH CENTRIFUGAL SEPARATOR WATER Emuw SUMP RECYCLE WATER COAL TO DRYER B. DOLLAR 3,158,101

FLOTATION DEVICE Filed Sept. 28. 1961 BILLY DOLLAR f f if u ATTORNEYS 3,158,1ttl FLQTATION DEVICE Billy Dollar, Box 3, Anawalt, W. Va. Filed Sept. 28, 1961, Ser. No. 141,435 '7 Claims. (Cl. 103--5) The present invention relates to equipment for the handling of fluids containing finely divided particles. More specifically, the invention relates to a device for assisting the pumping of liquids containing finely divided solids which are derived from flotation or similar separatory processes.

Flotation processes are now in wide use in many fields of technology where it is desired to classify and separate granular solids of varying particle size or different chemical or physical properties. For instance, metal ores, coal and other particulate materials are frequently subjected to such treatments in the course of their processing. According to one common procedure, the finely divided material is first treated in a conditioner where the particles are mixed with and coated by a flotation promoting agent, such as a mineral oil or the like. The conditioned solids are then introduced into a flotation cell. The solids are agitated in the flotation cell in the presence of a substantial volume of water. Due to the coating of the flotation promoter, the solids are buoyed up and are whipped into a froth by the agitation. The froth is then scooped off the top of the cell in the form of a watery foam overflow.

According to conventional practice, the solids-bearing froth or foam is then conducted to a centrifugal separator which breaks the froth into components, one an aqueous effluent and the other a solids concentrate. The solids are then directed to a drying station or are subjected to further processing, while the aqueous efl'luent is directed to a sump from which it is recycled by being pumped back to one of the earlier processing steps.

In the operation of such processes, a problem has arisen which has seriously impaired the efficiency and economy of the overall method. It has been found, that the aqueous effluent introduced into the sump still contains a significant amount of finely divided solids which are not removed by the centrifugal separator. These solids continually separate from the liquid in the sump, and form a layer or blanket on top of the water. Periodically, this layer of separated, finely, divided matter becomes so thick as to overflow the sump or cause clogging in the pump mechanism employed to recycle the water in the process.

When this occurs, it is necessary to stop the process and clean out the solid matter. Normally, a crew of men must be kept ready to take care of such stoppage when it occurs, so that a minimum of time is lost due to the shut down of the system. Even so, where a large tonnage of solids is being processed through the system, a temporary shutdown for a half hour to an hour causes a serious drop in the eiiiciency of the operation.

The importance of such shutdowns and their serious detriment to the overall process has long been recognized and a great many attempts have been made to overcome the difficulty. In the past, multiple outlets and pumps have been hooked up to the sumps in order to pump the water away more rapidly and thus prevent the build up of the solids layer on the top of the liquid. However, this has not proved to be entirely successful and, in addition, the extra pumps increase the equipment cost and power consumption. This in turn reduces the ethciency and economy of the process.

it has also been suggested, in an attempt to overcome the problem, that pump outlets be situated in the side of the sump at various points below the water level.

Modifications have also been made in the sluiceway United States Patent 'ly notable in processes for the treatment of coal.

3,158,1at Patented Nov. 24, 1964 leading into the sump, such as positioning the sluiceway at a steep angle with respect to the surface of the liquid and leading the outlet of the sluiceway below the water level so as to create turbulence as the effluent is introduced into the sump. Bafiie plates have also been placed in the sluiceway leading to the sump in order to create turbulence in an attempt to avoid separation or stratification of the coal layer. These attempts and others of a similar nature have all proved to be unsuccessful.

Accordingly, an object of the present invention is to provide a device for use in a sump of the type described which will enable the aqueous efiiuent to be pumped from the sump without separation and stratification of finely divided solids dispersed in the aqueous phase.

Another object of this invention is to provide a means for pumping a liquid containing finely divided dispersed solids from a sump without separation of the solids from the liquid and without the use of additional pumping devices or increased power consumption.

A further object of the present invention is to provide a device for pumping liquids containing finely divided, dispersed solids from a sump without separation of the solids from the liquid which device may be readily incorporated into standard sumps without expensive modifications and without altering the normal operation of the sump.

Another object of the invention is to provide a modified sump which enables solids bearing liquids to be received and pumped out without stratification or separation of the solids or overflowing of the liquid in the sump.

An additional object of the present invention is to provide a device which may be attached to the regular pump outlet line normally situated in sumps of the type in question and which may be employed with the same number of pumps and same horsepower of pump presently employed in such devices and which provides a means for pumping the liquid and dispersed solids without separation of the solids from the liquid.

A still further object of the present invention is to provide means for enabling liquids containing finely divided solids to be pumped from a sump without separation of the solids from the liquid and without the build up of a blanket or layer of the solids on top of the liquid, thus avoiding the periodic shutdown of the system and incident expense of cleaning the sump, the pump lines and the pump itself.

Other objects of the invention will become apparent by reference to the following description and accompanying drawings which represent, by way of example, a preferred embodiment of the invention and the best mode that has been contemplated for carrying out the invention.

In the drawings:

FIG. 1 represents a flow diagram of a portion of a coal treating process in which the present device may advantageously be employed.

FIG. 2 is a side view of the sump with the device positioned in the sump, the side wall of the sump being cut away.

FIG. 3 is a side cross-section of the device and lower portion of the sump.

FIG. 4 is a detailed top view of element 23 of the device shown in FIG. 3.

FIGURE 5 is a detailed view of the embodiment shown in FIGURE 3 without a cover plate across the mouth of the conical member.

The problem of Stratification or separation of finely divided solids from an aqueous phase has been especial- In the-steel industry, large tonnages of coal are employed in the various ore reduction processes carried out in the mills. A normal processing cycle for such coal involves separation by screening and washing of the various coal fractions with a water spray. A fraction containing coal particles having a diameter of about 65 mesh and finer is separated from the balance of the coal and is then subjected to a separate flotation treatment. Conventional pro-treatment for the small coal particles involves their introduction into a conditioner unit in which the small coal particles are mixed with and coated by a film of oil.

Reference may be had to the flow diagram of FIG. l for a better understanding of the general type of process being described.

The conditioned coal particles are then introduced into a flotation cell with a relatively large amount of water. Agitators are employed to whip up the coal and water into a froth which floats on the top of the water and is skimmed oil by paddles. From the flotation cells. the froth is distributed to a number of centrifugal separators, called filters or olishers. The polishers separate the froth into an aqueous component and a solids component. The solids component contains mostly coal and is then withdrawn by a conveyor and forwarded to a mixing unit where it is mixed with coal of size /1 inch and less from a dryer. The aqueous phase or component from the separator is directed into a sump from which it is continuously pumped and recycled through the system.

It is in this sump that serious problems arise which it is a specific object of the present invention to overcome.

FIG. 2 of the drawing shows a side view of a conventional sump employed in such treating systems and containing the device which forms the basis of the present invention.

According to the invention, the sump 1'0 has a bottom section '11 which preferably is narrower than the main body of the sump. A liquid withdrawal unit 12 is positioned in the section 11 and is attached to the end of the intake line 13 of pump 14.

It will be noted that the level of the liquid 15 in sump '10 stands somewhat above the level of the liquid withdrawal unit 12 and may frequently stand much higher than is shown in FIGS. 2 and 3.

'Sluiceaway 16 communicates with the sump and provides means for the introduction of the water-,coalefiluent from the centrifugal separators.

According to a preferredembodiment of the invention, a booster line 18 is joined to the pump output line 17 for returning .a jet of water under pressure to the liquid withdrawal assemb y .1

The liquid withdrawal unit 12 which forms one of the outstanding features of the present invention may be seen in greater detail by referring to FIGS. 3 and 4 of the drawing.

It will be seen that the liquid withdrawal unit 12 comprises a hollow conical member 20 which may be attached to the pump intake line 13 by means of a right angle coupling member 21.

The wide end or mouth of the hollow conical member is pointed downwardly into the narrow bottom sec .tion 11 of the sump 10.

It has been found highly desirable, in order to increase the efficiency of the withdrawal unit 12, that the mouth of the conical member 2.0 be provided with a series of louvered slots 22 at the wide end of the conical member surrounding the mouth of the conical element.

A cover plate 23 is situated in the mouth of the conical member 20 and it also is preferably provided with a plurality of louvered or radical slots 24.

Cover plate 23 has a central aperture 25 for the passage of booster nozzle 26. For maximum efficiency, booster nozzle 26 is terminated close to the junction of the conical member 20 with the coupling member 21.

In operation, the aqueous eifiuent from the polisher or centrifugal separator units is delivered by sluiceway 16 to the sump 10. The level of the liquid 15 in the sump is maintained above the liquid withdrawal assembly 12.

Pump 14 is continuously in operation and sucks up the liquid and the entrained or dispersed solids without separation of solids by virtue of the unique action of the liquid withdrawal assembly 12. The intake louvers or slots in the conical member 20 and the cover plate 23 create a turbulence and agitation Within the sump which prevents separation of the solids.

It has been found that the liquid withdrawal assembly normally operates satisfactorily without the use of the booster nozzle, but occasionally, where the efiluent inflow is exceptionally heavy and the pump begins to fall behind, use of the booster 26 may be helpful. in such instances, the valve 27 is operated to tap off a portion of the fluid from line 17 which is being returned for recycling through the process. This liquid is forced through line 18 and directed through nozzle 26 into the liquid withdrawal assembly. Another source of liquid under pressure might be employed although it is very convenient to tap the output line of the pump. This booster effect enables the pump and liquid withdrawal assembly to keep up quite easily with the necessary rate of liquid withdrawal and the maintenance of a satisfactory turbulence in the sump.

For optimum results, slots 22 in conical member 20 and slots 24 in plate 23 are provided with louvers 30 and 31 respectively and the louvers add to the swirling elfect created by the device as the water is drawn in through it. The louvers may be formed by the same operation in which the slots are formed by leaving the punched out material partially attached to the wall of the conical member 20 or plate 23.

As will be seen by reference to FIGURE 5, the device will also function satisfactorily without cover plate 23.

The proposed device may be readily manufactured from sheet metal and commercially available pipe and coupling elements. Installation of the liquid withdrawal unit in existing sump apparatus may readily be made by providing a screw threaded connector for linking the withdrawal unit to an existing pump intake line.

Considering, for example, that the sump shown in FIG. 2 is of a generally conventional nature and that it is provided with only a withdrawal line 13 and a pump 14 of about 30 horsepower, the sump will normally have to be closed down periodically and cleaned out to remove the accumulation' of coal which will clog the sump, the withdrawal lines and the pump or build up a blanket of coal on top of the liquid in the sump and result in overflow. By operating with the same withdrawal line 13 and with the same pump 14, .the accumulation of a layer of coal on top of the water in the sump can be prevented simply by attaching the novel liquid withdrawal unit to the pump intake line. With the liquid withdrawal unit in place, the removal of water from the sump and its recycling through the process proceeds without interruption and without the build up of or the strati fication of coal in the sump. The booster return line 18 and nozzle 26 may be added to increase the efficiency of the unit.

In some circumstances, the device is effective without cover plate 23, but plate 2 3 greatly enhances the efliciency of the device and is employed in a preferred embodiment of the device.

The device of the invention assists pumping of liquidsolid slurries from sumps of any structure. The sump need not have a restricted or narrow bottom section as shown in FIGS. 2 and 3, but the device is more effective in sumps of such configuration.

Other specific embodiments of the present invention may be constructed by those skilled in the art' without departing from the spirit of the invention and without departing from the scope of the following claims.

What is claimed is:

1. An apparatus for assisting the pumping of liquidsolid slurries from vessels containing such slurries comprising a hollow conical member, said hollow conical member having an aperture at the apex, a fluid conduit communicating at one end with said aperture and attached to said hollow conical member at said aperture, a pump, said conduit communicating at its other end with the intake of said pump for withdrawing a liquidsolid slurry from said vessel, said hollow conical member having an open mouth communicating with said slurry and a series of louvered slots through the wall of said hollow conical member positioned around said open mouth.

2. The apparatus of claim 1 further comprising a slotted plate across said open mouth of said hollow conical member.

3. An apparatus for assisting the pumping of liquidsolid slurries from vessels containing such slurries comprising a hollow conical member, said hollow conical member having an aperture at the apex, a fluid conduit communicating at one end with said aperture and attached to said hollow conical member at said aperture, a pump, said conduit communicating at its other end with the intake of said pump for withdrawing a liquidsolid slurry from said vessel, said hollow conical member having an open mouth communicating with said slurry, a series of louvered slots through the wall of said hollow conical member positioned around said open mouth, a slotted plate aflixed across said open mouth, an aperture in said plate, a second conduit communicating at one end with a source of fluid under pressure, a second end of said second conduit communicating with the interior of said hollow conical member, a nozzle on said second end of said second conduit terminating adjacent said apex of said hollow conical member, said aperture in said plate positioned to permit passage of said second conduit into said hollow conical member.

4. In combination, a sump for receiving a solids bearing liquid slurry and a hollow conical member in the bottom of said sump, a pump, a fluid conduit connecting the apex of said hollow conical member with said pump for pumping out the contents of said sump, said hollow conical member having an open base surrounded by a series of louvered slots through the side walls of said hollow conical member.

5. In combination, a sump for receiving a solids bearing liquid slurry and a hollow conical member in the bottom of said sump, said hollow conical member having a plate across the mouth, said plate having a central aperture and a series of radial louvered slots and said hollow conical member having a series of louvered slots around said mouth, a pump, a first fluid conduit connecting the apex of said hollow conical member with said pump for pumping out the contents of said sump, a second conduit passing through said central aperture and communicating at one end with the output conduit from said pump, the second end of said second conduit communicating with the interior of said hollow conical member, a nozzle on said second end of said second conduit for creating a jet of fluid directed towards said first fluid conduit.

6. An apparatus for assisting the pumping from a sump of aqueous slurries bearing finely divided coal particles to prevent separation of the coal particles comprising a hollow conical member positioned below the water level in said sump, a pump, said hollow conical member having an outlet at its apex in fluid communication with the intake of said pump for pumping out the contents of said sump, said hollow conical member having an open mouth facing the bottom of said sump and said hollow conical member having a series of louvered slots surrounding said open mouth.

7. An apparatus for assisting the pumping from a sump of aqueous slurries bearing finely divided coal particles to prevent separation of the coal particles comprising a hollow conical member positioned below the water level in said sump, a pump, said hollow conical member having an outlet at its apex in fluid communication with the intake of said pump for pumping out the contents of said sump, said hollow conical member having a mouth facing the bottom of said sump, said hollow conical member having a series of louvered slots surrounding said mouth, a plate across said mouth, said plate having a central aperture and a series of radial, louvered slots, a fluid conduit through said central aperture, a nozzle at one end of said fluid conduit directed towards said apex and the other end of said fluid conduit in fluid communication with the output of said pump.

References Cited in the file of this patent UNITED STATES PATENTS 1,437,939 Green Dec. 15, 1922 2,263,864 Avigdor Nov. 25, 1941 2,662,486 Hillger Dec. 15, 1953 2,695,564 Nagle Nov. 30, 1954 2,740,616 Walden Apr. 3, 1956 2,890,659 Haentjens June 16, 1959 FOREIGN PATENTS 78,575 Denmark Nov. 29, 1954 225,843 Great Britain Dec. 31, 1925 639,524 France Mar. 10, 1928 

1. AN APPARATUS FOR ASSISTING THE PUMPING OF LIQUIDSOLID SLURRIES FROM VESSELS CONTAINING SUCH SLURRIES COMPRISING A HOLLOW CONICAL MEMBER, SAID HOLLOW CONICAL MEMBER HAVING AN APERTURE AT THE APEX, A FLUID CONDUIT COMMUNICATING AT ONE END WITH SAID APERTURE AND ATTACHED TO SAID HOLLOW CONICAL MEMBER AT SAID APERTURE, A PUMP, SAID CONDUIT COMMUNICATING AT ITS OTHER END WITH THE INTAKE OF SAID PUMP FOR WITHDRAWING A LIQUIDSOLID SLURRY FROM SAID VESSEL, SAID HOLLOW CONICAL MEMBER HAVING AN OPEN MOUTH COMMUNICATING WITH SAID SLURRY AND A SERIES OF LOUVERED SLOTS THROUGH THE WALL OF SAID HOLLOW CONICAL MEMBER POSITIONED AROUND SAID OPEN MOUTH. 